PURPOSE: To produce a cold rolled steel sheet having superior workability and high strength and excellent in galvanizing characteristic by using an ultralow carbon steel containing Ti and Nb as a base, actively adding Mn and Cr to increase strength, and counteracting the plating harmfulness of Si and P incorporated in order to provide strength.
CONSTITUTION: A slab which has a composition consisting of, by weight, 0.0003-0.01% C, >0.03-0.8% Si, 0.01-0.12% P, 0.001-O.015% S, 0.01-0.1% Al, 0.0005-0.0060% N, >0.5-3.0% Mn and/or 0.1-3.0% Cr, further 0.005-0.10% Ti and/or 0.003-0.10% Nb, and the balance essentially Fe and satisfying Mn≤3(Si+1/20Cr)-1.0 and 35P-1.5 ≤(Mn+1/20Cr)≤75P+2.5 is hot-rolled. Subsequently, cold rolling is performed, and then inline annealing type continuous hot dipping is done.
YOSHINAGA NAOKI
AKISUE OSAMU
KUROSAWA SUSUMU
JPH02163346A | 1990-06-22 | |||
JPH02163318A | 1990-06-22 |